Pollack R J, Lok J B, Donnelly J J
Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia 19104.
J Parasitol. 1988 Jun;74(3):353-9.
Reduced glutathione (GSH), but not its oxidized form (GSSG), stimulated development of Onchocerca lienalis microfilariae to the late first-larval stage in vitro. The degree and frequency of development was dose-related with a peak of activity at 15 mM, a concentration that is similar to known intracellular levels of GSH. To determine the mode(s) of action of this multifunctional compound, other reducing agents (L-cysteine, dithiothreitol), cysteine delivery agents (N-acetyl-L-cysteine, L-thiazolidine-4-carboxylic acid, L-2-oxothiazolidine-4-carboxylic acid), cysteine analogues (S-methyl-L-cysteine, D-glucose-L-cysteine, cysteine ethyl ester), free-component amino acids of GSH (glutamic acid, cysteine, and glycine), a specific metabolic inhibitor of gamma-glutamyl synthetase (buthionine sulfoximine), and an inhibitor of gamma-glutamyl transpeptidase (gamma-glutamyl glutamic acid) were also tested at concentrations of 0.01-50 mM in this system. N-acetyl-L-cysteine at 1-5 mM and D-glucose-L-cysteine at 2.5-10 mM significantly enhanced development. In contrast to those worms maintained in GSH-supplemented medium, microfilariae exposed to GSH for only the first 24 hr showed no enhancement by day 7 in culture. Neither buthionine sulfoximine nor gamma-glutamyl glutamic acid at 0.01-35 mM inhibited the effects of 15 mM GSH or 1 mM N-acetyl-L-cysteine. Results indicate that GSH or other cysteine analogues possessing a free sulfhydryl group must be present in the extranematodal environment to support microfilarial differentiation in vitro.
还原型谷胱甘肽（GSH）而非其氧化形式（GSSG），在体外可刺激链尾盘尾丝虫微丝蚴发育至第一期幼虫晚期。发育的程度和频率与剂量相关，在15 mM时活性达到峰值，该浓度与已知的细胞内GSH水平相似。为了确定这种多功能化合物的作用方式，还在该系统中测试了其他还原剂（L-半胱氨酸、二硫苏糖醇）、半胱氨酸递送剂（N-乙酰-L-半胱氨酸、L-噻唑烷-4-羧酸、L-2-氧代噻唑烷-4-羧酸）、半胱氨酸类似物（S-甲基-L-半胱氨酸、D-葡萄糖-L-半胱氨酸、半胱氨酸乙酯）、GSH的游离成分氨基酸（谷氨酸、半胱氨酸和甘氨酸）、γ-谷氨酰合成酶的特异性代谢抑制剂（丁硫氨酸亚砜胺）以及γ-谷氨酰转肽酶抑制剂（γ-谷氨酰谷氨酸），浓度范围为0.01 - 50 mM。1 - 5 mM的N-乙酰-L-半胱氨酸和2.5 - 10 mM的D-葡萄糖-L-半胱氨酸显著促进了发育。与在补充GSH的培养基中培养的蠕虫不同，仅在最初24小时暴露于GSH的微丝蚴在培养第7天时没有表现出促进作用。0.01 - 35 mM的丁硫氨酸亚砜胺和γ-谷氨酰谷氨酸均未抑制15 mM GSH或1 mM N-乙酰-L-半胱氨酸的作用。结果表明，在体外支持微丝蚴分化的线虫外环境中，必须存在GSH或其他具有游离巯基的半胱氨酸类似物。
